Holy Thursday (Catholic/ Christian Protestant/ The Church of Jesus Christ of Latter-day Saints)

Holy Thursday is the commemoration of the Last Supper of Jesus Christ, when, prior to his arrest and crucifixion, he established the practice of communion, which is considered a sacrament among most Christian communities. Later that evening, he prays in the Garden of Gethsemane.
More information from the Catholic Church
More information from The Church of Jesus Christ of Latter-day Saints
More information from the Christian Methodist Episcopal Church